Natural, native gums are highly functional ingredients that contribute to the texture, stability and other physical attributes of processed foods. However, sometimes, they need physical or chemical modifications to extend functionality, or enable them to overcome various processing and shelf-life challenges. For example, a few gums naturally have a small affinity for fat; however, modification improves this attribute, enabling them to function as emulsifiers by dispersing fat in aqueous solutions.
Gum basics
All gums must be hydrated to function in a food system, so they are characterized as hydrocolloids, with “hydro” meaning water and “colloid” referring to the dispersion of small particles in another medium. Gums can structure water, thereby allowing other ingredients in a food system to be dispersed and suspended in an aqueous medium.
“The food-ingredient category called gums refers to high-molecular-weight, long-chain, carbohydrate-based polymers that are capable of modifying aqueous solutions by creating viscosity, as well as sometimes gelling,” says Allen Freed, CEO, Gum Technology, Tucson, AZ. “They can create a wide range of rheologies, depending on the choice of single gum or the synergistic blend of more than one gum.”
Mar Nieto, senior principal scientist, TIC Gums, Belcamp, MD, further explains, “Gum polymers are either linear polysaccharides consisting of one sugar monomer, or linear and consisting of a repeating dimer; linear with another sugar substitution or side chain on the linear backbone; or branched consisting of a mixture of different sugars.
“In addition, they can exhibit either a neutral charge (e.g., acetate esters, methyl ethers, other neutral sugars), negative charge (e.g., carboxylate, sulfate groups), or positive charge (e.g., amino groups) due to the presence of various chemical groups attached to individual monosaccharide units,” continues Nieto. “All of these structural features of gums contribute to their differences in solubility; synergy or incompatibility with each other or with other ingredients (e.g., proteins, minerals, acids and lipids); thickening, gelling and emulsifying properties; and their film-forming properties.”
Freed says: “Plant-based gums include those derived from seeds, such as guar and locust bean. Cellulose gum is derived from the fibrous material in plants.
“Tree exudates are a fancy name for sap, like maple syrup,” continues Freed. “The difference between maple syrup and gums like gum arabic (acacia gum) and gum tragacanth is that these saps harden as they ooze from the tree. The hardened sap is picked off the tree and ground down to a fine flour. Each has its own unique attributes.”
There are also marine and microbial food-gum sources. “You will see names like carrageenan, alginate and agar. These are marine gums,” says Freed. “Xanthan gum is produced by microorganisms and is considered to be just as natural as those gums that come from plants and the earth’s waters.”
While many gums are used in a natural, albeit refined state, others need a helping hand to improve on nature.
From the lab
As mentioned, physical or chemical modifications can extend hydrocolloid functionality. A few gums have “more-mysterious names, products that are the creation of a person in a white coat,” says Freed. “The most common of these is probably carboxymethyl cellulose (CMC), which starts out as cellulose but is chemically modified to enhance functionality.”